Project description:Obesity is characterized by abnormal adipose development and disruptive energy metabolism, and with many factors involved. Oxytocin receptor (OXTR) affects social behaviors, mammary gland development and cancers. In this study, transgenic overexpression of OXTR under β-actin promoter (++Oxtr) exhibited a lean phenotype with reduced fat accumulation and without significant change in food consumption. OXTR overexpression enhanced energy expenditure, adaptive thermogenesis and glucose tolerance. Morphologically, OXTR overexpression displayed a browning phenotype in adipose tissue accompanied by higher cell counts and smaller adipocytes. Gene expression analysis revealed elevated levels of Brown Adipose Tissue (BAT) markers, fatty acid transport proteins and glucose transporters in adipose tissues. High OXTR ameliorated high-fat-diet induced obesity with improvement of metabolic parameters. Furthermore, OXTR overexpression led to an activation of PPAR signaling, increased energy consumption, reduced fat accumulation and weight loss. We have identified OXTR to be a critical regulator of energy metabolism and thermogenesis. That OXTR enhances adaptive thermogenesis and energy metabolism may present a novel therapeutic target for metabolic disorders.
Project description:Obesity increases circulating levels of the bioactive sphingolipid metabolite sphingosine-1-phosphate (S1P). Here, we identify adipocyte-expressed sphingosine kinase 2 (SPHK2), an enzyme that produces S1P, as a regulator of adipose tissue browning. Mice with adipocyte-specific deletion of Sphk2 were protected from Western diet-induced obesity concomitantly with elevated energy expenditure and browning of subcutaneous fat and enhanced expression of Ucp1 and key thermogenic genes, resulting in reduced adiposity and hepatic steatosis, improved glucose tolerance and insulin sensitivity. Mechanistically, obesogenic diet promoted nuclear localization of SPHK2 in adipocytes, where it cooperated with transcription factors to suppress the thermogenic transcriptome. Adipocyte SPHK2 was responsible for maintaining homeostatic circulating S1P levels and driving the pathogenic rise of S1P in response to obesogenic diet. Our findings reveal a distinct role of adipocyte SPHK2 in regulation of the thermogenic program important for whole-body metabolic homeostasis and energy expenditure and highlights SPHK2 as a potential therapeutic target for treatment of metabolic disorders.
Project description:Obesity increases circulating levels of the bioactive sphingolipid metabolite sphingosine-1-phosphate (S1P). Here, we identify adipocyte-expressed sphingosine kinase 2 (SPHK2), an enzyme that produces S1P, as a regulator of adipose tissue browning. Mice with adipocyte-specific deletion of Sphk2 were protected from Western diet-induced obesity concomitantly with elevated energy expenditure and browning of subcutaneous fat and enhanced expression of Ucp1 and key thermogenic genes, resulting in reduced adiposity and hepatic steatosis, improved glucose tolerance and insulin sensitivity. Mechanistically, obesogenic diet promoted nuclear localization of SPHK2 in adipocytes, where it cooperated with transcription factors to suppress the thermogenic transcriptome. Adipocyte SPHK2 was responsible for maintaining homeostatic circulating S1P levels and driving the pathogenic rise of S1P in response to obesogenic diet. Our findings reveal a distinct role of adipocyte SPHK2 in regulation of the thermogenic program important for whole-body metabolic homeostasis and energy expenditure and highlights SPHK2 as a potential therapeutic target for treatment of metabolic disorders.
Project description:We report mRNA seq during time course of white preadipocyte browning from WT and HMGN1 and HMGN2 double knockout (DKO) mice . Moreover, we support our finding that loss of HMGN promotes white adipocyte browning with RNA seq of WT and DKO MEFs transdifferentiation into brown-like adipocytes.
Project description:We report single-cell RNA seq (scRNA seq) at day 0 and day 6 of white preadipocyte browning from WT and HMGN1 and HMGN2 double knockout (DKO) mice. This supports our finding that loss of HMGN promotes white adipocyte browning with RNA seq of WT and DKO MEFs transdifferentiation into brown-like adipocytes.
Project description:Brown adipose tissue (BAT) is a central thermogenic organ that enhances energy expenditure (EE) and cardiometabolic health. However, regulators that specifically increase the number of thermogenic adipocytes are still an unmet need. Here, we show by phosphoproteomics that cAMP activates distinct signaling pathways in brown progenitors, with the cAMP-EPAC1 axis enhancing proliferation and differentiation of thermogenic but not white adipocytes. Further analysis revealed that a specific subpopulation of preadipocytes that are PDGFRα-positive express EPAC1. In vivo, pharmacological activation of EPAC1 enhances BAT growth and browning of white fat, leading to increased EE and reduced diet-induced adiposity. In contrast, mice lacking EPAC1 in PDGFRα-positive preadipocytes show the opposite phenotype. Importantly, EPAC1 activation enhances proliferation and differentiation of human brown adipocytes and human brown fat organoids. Interestingly, a coding variant in EPAC1 that positively correlates with BMI abolishes norepinephrine-induced proliferation of brown adipocytes. Thus, EPAC1 might be an attractive target to enhance thermogenic adipocyte number and EE to combat metabolic diseases.
Project description:The adipose tissue is a key site regulating energy metabolism. One of the contributing factors behind this is browning of white adipose tissue (WAT), however, knowledge of the intracellular determinants of browning process remains incomplete. By generating adipocyte-specific Senp2 knockout (Senp2-aKO) mice, here we showed that SENP2 negatively regulates browning by de-conjugating SUMO from C/EBPβ. Senp2-aKO mice were resistant to diet-induced obesity and insulin resistance due to increased energy expenditure and heat production. Senp2 knockout promoted beige adipocyte accumulation in inguinal WAT by upregulation of thermogenic gene expression. In addition, SENP2 knockdown promoted thermogenic adipocyte differentiation of precursor cells isolated from inguinal and epididymal WATs. Mechanistically, sumoylated C/EBPβ, a target of SENP2, suppressed expression of HOXC10, a browning inhibitor, by recruiting a transcriptional repressor DAXX. These findings indicate that a SENP2-C/EBPβ-HOXC10 axis operates for the control of beige adipogenesis in inguinal WAT.
Project description:The adipose tissue is a key site regulating energy metabolism. One of the contributing factors behind this is browning of white adipose tissue (WAT), however, knowledge of the intracellular determinants of browning process remains incomplete. By generating adipocyte-specific Senp2 knockout (Senp2-aKO) mice, here we showed that SENP2 negatively regulates browning by de-conjugating SUMO from C/EBPβ. Senp2-aKO mice were resistant to diet-induced obesity and insulin resistance due to increased energy expenditure and heat production. Senp2 knockout promoted beige adipocyte accumulation in inguinal WAT by upregulation of thermogenic gene expression. In addition, SENP2 knockdown promoted thermogenic adipocyte differentiation of precursor cells isolated from inguinal and epididymal WATs. Mechanistically, sumoylated C/EBPβ, a target of SENP2, suppressed expression of HOXC10, a browning inhibitor, by recruiting a transcriptional repressor DAXX. These findings indicate that a SENP2-C/EBPβ-HOXC10 axis operates for the control of beige adipogenesis in inguinal WAT.
Project description:Here we have characterized the transcriptional processes underlying the formation of human brown in white (i.e. brite) adipocytes using a genome-wide approach. We show that the browning process is associated with reprogramming of peroxisome proliferator-activated receptor γ (PPARγ) binding to form brite adipocyte-selective PPARγ super-enhancers that appear to play a key role in activation of brite adipocyte-selective genes. We identify the KLF11 gene based on its association with a PPARγ super-enhancer and show that KLF11 is a novel browning factor directly induced by rosiglitazone and required for the activation of brite adipocyte-selective gene program by rosiglitazone. Genome-wide profiling of Dnase I hypersenstive (DHS) sites, epigenomic marks, transcription factor and co-factor binding, and gene expression in hMADS white and brite adipocytes